1. Field of the Invention
The present invention relates to a method for making semiconductor devices.
2. Background of the Invention
The dual damascene process is widely used in semiconductor device fabrication. As part of fabricating the semiconductor device using the dual damascene fabrication process a conductive layer is formed on a substrate. Next, a barrier layer made from either silicon nitride or silicon carbide is deposited on the conductive layer to act as an etch stop. Shunt metal layers such as cobalt or tungsten may be used as a copper diffusion barrier.
The use of silicon nitride by itself as a barrier layer is undesirable due to its high dielectric constant (k).
The use of silicon carbide by itself as a barrier layer is also undesirable because silicon carbide has organic components and these organic components cause xe2x80x9cvia poisoningxe2x80x9d. As a result, these contaminants cause an undesirably high via resistance. Moreover, Silicon carbide is not a hermetic sealer, allowing undesirable moisture to diffuse through it causing undesirable effects in the semiconductor device.